1666687 has 4 divisors (see below), whose sum is σ = 1818216. Its totient is φ = 1515160.

The previous prime is 1666657. The next prime is 1666711. The reversal of 1666687 is 7866661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7866661 = 11 ⋅715151.

It is a cyclic number.

It is not a de Polignac number, because 1666687 - 2⁷ = 1666559 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666607) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 75748 + ... + 75769.

It is an arithmetic number, because the mean of its divisors is an integer number (454554).

2^1666687 is an apocalyptic number.

1666687 is a deficient number, since it is larger than the sum of its proper divisors (151529).

1666687 is a wasteful number, since it uses less digits than its factorization.

1666687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151528.

The product of its digits is 72576, while the sum is 40.

The square root of 1666687 is about 1291.0023237779. The cubic root of 1666687 is about 118.5635923044.

The spelling of 1666687 in words is "one million, six hundred sixty-six thousand, six hundred eighty-seven".